Method for transmitting and receiving system information via a broadcast channel (BCH) and a downlink shared channel (DL—SCH)

ABSTRACT

A method for receiving system information via a broadcast control channel (BCCH) to which a broadcast channel (BCH) and a downlink shared channel (DL_SCH) are mapped, the method including receiving, by a user equipment (UE), a block of first system information from a base station via the BCH, and receiving, by the UE, a first block of second system information from the base station via the DL_SCH. The first block of second system information is scheduled with a fixed time offset. The method further includes receiving, by the UE, a plurality of second blocks of second system information from the base station via the DL_SCH.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.14/099,538 filed on Dec. 6, 2013, which is a Continuation of U.S.application Ser. No. 12/577,136 filed on Oct. 9, 2009 (now U.S. Pat. No.8,798,635), which is a Continuation of co-pending U.S. application Ser.No. 12/523,869 filed on Jul. 21, 2009, which is the national phase ofPCT International Application No. PCT/KR2008/000532 filed on Jan. 29,2008, which claims priority to U.S. Provisional Application Nos.60/887,550 filed on Jan. 31, 2007, and 60/900,652 filed on Feb. 8, 2007,and which claims priority to Application No. 10-2008-0008631 filed inthe Republic of Korea on Jan. 28, 2008. The contents of all of theseapplications are hereby incorporated by reference as fully set forthherein in their entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to transmission and reception of systeminformation and, more particularly, to transmission and reception ofsystem information in an E-UTRAN system.

Discussion of the Related Art

FIG. 1 illustrates an exemplary structure of a general E-UTRAN (EvolvedUniversal Terrestrial Radio Access Network) system according to therelated art and the present invention.

The E-UTRAN system as shown in FIG. 1 has been evolved from theconventional UTRAN system and a third generation partnership project(3GPP) currently proceeds with basic standardization operations. TheE-UTRAN system is also called an LTE (Long Term Evolution) system

The E-UTRAN system includes base stations (eNode Bs or eNBs) 21 to 23,and the eNBs 21 to 23 are connected via an X2 interface. The eNBs 21 to23 are connected with a terminal (or user equipment (UE)) 10 via a radiointerface and connected to an EPC (Evolved Packet Core) 30 via an S1interface.

Layers of a radio interface protocol between the terminal 100 and anetwork may be divided into a first layer L1, a second layer L2, and athird layer L3 based on the three lower layers of an open systeminterconnection (OSI) standard model which is widely known incommunication systems. A physical layer belonging to the first layeramong the three lower layers provides an information transfer serviceusing a physical channel, and a radio resource control (RRC) layerpositioned at the third layer serves to control radio resources betweenthe UE and the network. For this, the RRC layer exchanges an RRC messagebetween the UE and the network.

FIG. 2 illustrates the structure of a radio interface protocol betweenthe UE and a UTRAN (UMTS Terrestrial Radio Access Network) according tothe 3GPP radio access network (RAN) standards. FIG. 3 is an exemplaryview of a physical channel.

The radio interface protocol as shown in FIG. 2 has horizontal layerscomprising a physical layer, a data link layer, and a network layer. Theradio interface protocol has vertical planes comprising a user plane(U-plane) for transmitting data information and a control plane(C-plane) for transferring control signaling.

The protocol layers in FIG. 2 may be divided into a first layer L1, asecond layer L2, and a third layer L3 based on the three lower layers ofthe open system interconnection (OSI) standard model which is widelyknown in communication systems.

The physical layer, namely, the first layer L1, provides informationtransfer service to an upper layer by using a physical channel. Thephysical layer is connected to an upper layer called a medium accesscontrol (MAC) layer via a transport channel. The physical layertransfers data to the MAC layer via the transport channel.

Data is transferred via the physical channel between different physicallayers, namely, between a physical layer of a transmitting side and thatof a receiving side. The physical channel is demodulated according to anOFDM (Orthogonal Frequency Division Multiplexing) method, and utilizestime and frequency as radio resources.

The second layer L2 is divided into two lower layers. Namely, the secondlayer is divided into a MAC layer and an RLC layer. The MC layerprovides a service to the RLC layer, the upper layer, via a logicalchannel. The RLC layer supports a reliable data transmission. Here, thefunction of the RLC layer may be implemented as a function block withinthe MAC layer. In such a case, the RLC may not exist.

Although not shown, the second layer further comprises a PDCP layer. ThePDCP layer performs a function called header compression that reducesthe size of a header of an IP packet, which is relatively large andincludes unnecessary control information, in order to effectivelytransmit the IP packet such as an IPv4 or IPv6 in a radio interfacehaving a smaller bandwidth.

The RRC layer corresponding to the third layer is defined only in thecontrol plane, and controls a logical channel, a transport channel and aphysical channel in relation to configuration, reconfiguration, and therelease of radio bearers (RBs). In this case, the RBs refer to a serviceprovided by the second layer for data transmission between the UE 10 andthe UTRAN. When an RRC connection is made between the RRC layer of theUE 10 and that of the radio network, the UE 100 is defined to be in anRRC connected mode, or otherwise, the UE 100 is defined to be in an idlemode.

A NAS (Non-Access Stratum) layer exists at an upper position of the RRClayer. The NAS layer performs a function of session management, mobilitymanagement, etc.

The physical channel, the transport channel, and the logical channelwill now be described in more detail.

First, each cell formed by each of the eNBs 21 to 23 is set with one ofbandwidths 1.25 Mhz, 2.5 Mhz, 5 Mhz, 10 Mhz, 20 Mhz, etc., and providesdownlink or uplink physical channel to several terminals. In this case,the mutually different cells may be set to provide each differentbandwidth.

As noted with reference to FIG. 3, the physical channel comprisesseveral sub-frames of a time axis and several sub-carriers of afrequency axis. Here, a single sub-frame comprises a plurality ofsymbols at the time axis. A single sub-frame comprises a plurality ofresource blocks, and a single resource block comprises a plurality ofsymbols and a plurality of sub-carriers. Each sub-frame may useparticular sub-carriers of particular symbols (e.g., a first symbol) ofa corresponding sub-frame for a PDCCH (Physical Downlink ControlChannel), namely, an L1/L2 control channel. A single sub-frame is 0.5ms, and a TTI (Transmission Time Interval), a unit time for datatransmission, is 1 ms corresponding to two sub-frames.

Next, the transport channel includes a downlink transport channel fortransmitting data from a network to a terminal and an uplink transportchannel for transmitting data from the terminal to the network. Thedownlink transport channel for transmitting data from the network to theterminal includes a broadcast channel (BCH) for transmitting systeminformation, a paging channel (PCH) for transmitting a paging message,and a downlink shared channel (SCH) for transmitting user traffic or acontrol message. The downlink multicast, traffic of a broadcast serviceor a control message may be transmitted via the downlink SCH or aseparate downlink MCH (Multicast Channel).

The uplink transport channel for transmitting data from the terminal tothe network includes a random access channel (RACH) for transmitting aninitial control message and an uplink SCH for transmitting other usertraffic or a control message.

The logical channel is mapped to the transport channel and includes aBCCH (Broadcast Channel), a PCCH (Paging Control Channel), a CCCH(Common Control Channel), an MCCH (Multicast Control Channel0, an MTCH(Multicast Traffic Channel), etc.

In the above-described related art, the base station transmits thesystem information via the static channel, namely, via the BCH. However,in order to statically transmit the system information, allocation ofradio resources needs to be always maintained. This makes the radioresources used very inefficiently, and thus, the radio resources areinsufficient always.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to reduce a waste ofradio resources by dynamically transmitting system information.

To achieve the above object, in the present invention, systeminformation is divided into first to third blocks, the first block istransmitted via a static broadcast channel and the second and thirdblocks are transmitted via a dynamic broadcast channel, therebyeffectively transmitting the system information.

In detail, in order to achieve the above object, there is provided amethod for transmitting system information from a base station toterminals of a cell, including: transmitting a first block of systeminformation to a terminal via a static broadcast channel; transmitting asecond block of the system information to the terminal via a dynamicbroadcast channel in a certain time interval after the first block istransmitted; and transmitting a third block of the system information tothe terminal via the dynamic broadcast channel.

In order to achieve the above object, there is also provided a methodfor receiving system information by a mobile terminal from a basestation, including: receiving a first block of system information fromthe base station via a static broadcast channel; receiving a secondblock of the system information from the base station via a dynamicbroadcast channel in a certain time interval according to a valueincluded in the first block after the first block is received; andreceiving a third block of the system information from the base stationvia the dynamic broadcast channel based on information included in thesecond block.

Preferably, the terminal may receive information about the second blockvia the first block, and receive information about the third block viathe second block.

Preferably, the terminal may acquire control information regarding thethird block via the second block and via a control channel of thedynamic broadcast channel.

Preferably, the dynamic broadcast channel is a channel that shares radioresources with user data, and the static broadcast channel is a channelthat does not share radio resources with the user data.

Preferably, the static broadcast channel is a channel that does notshare radio resources with data other than the system information.

Preferably, the dynamic broadcast channel is a channel whose transferrate can be changed, and the static broadcast channel is a channel whosetransfer rate is not changed.

Preferably, the dynamic broadcast channel is a channel that isaccompanied with a supplementary control channel, and the staticbroadcast channel is a channel that is not accompanied with asupplementary control channel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary view showing the structure of a E-UTRAN, therelated art mobile communication system;

FIG. 2 is an exemplary view showing the structure of a radio interfaceprotocol between a terminal and a UTRAN based on 3GPP radio accessnetwork standards;

FIG. 3 is an exemplary view showing a physical channel;

FIG. 4 is an exemplary view showing a terminal 100 and a base station(or eNB) 200 according to the present invention; and

FIG. 5 is an exemplary view showing transmission of system informationaccording to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The embodiment of the present invention will now be described withreference to the accompanying drawings.

FIG. 4 is an exemplary view showing a terminal 100 and a base station(or eNB) 200 according to the present invention, and FIG. 5 is anexemplary view showing transmission of system information according tothe present invention.

As noted with reference to FIG. 4, a base station (or eNB) 200 accordingto the present invention divides system information into first to thirdblocks, transmits the first block via a static broadcast channel and thesecond and third blocks via a dynamic broadcast channel, to thuseffectively transmit the system information. Here, the static broadcastchannel may be a channel that does not share radio resources with dataother than the system information. The dynamic broadcast channel may bea channel that shares radio resources with user data. In addition, thedynamic broadcast channel may be a channel whose transfer rate isvaried, and the static broadcast channel maybe a channel that has afixed transfer rate. Or, the dynamic broadcast channel may be a channelthat is accompanied with a control channel, and the static broadcastchannel may be a channel that is not accompanied with a control channel.For example, the static broadcast channel may be a P-BCH (PrimaryBroadcast Channel), and the dynamic broadcast channel may be a D-BCH(Dynamic Broadcast Channel), an S-BCH (Secondary Broadcast Channel), ora DL SCH (Downlink Shared Channel).

In detail, the base station (or eNB) 200 divides the system informationinto a first block, i.e., a PIB (Primary system Information Block), asecond block, i.e., an MIB (Master secondary system Information Block),a third block, i.e., an SIB (Secondary system Information Block). Here,the PIB provides information about the MIB, and the MIB providesinformation about the SIB.

Accordingly, the terminal 100 can obtain the information about the MIBby receiving the PIB from the base station (or eNB) 200 and receive theMIB using the obtained information about the MIB. In addition, theterminal can obtain the information about the SIB by receiving the MIBand receive the SIB using the obtained information about the SIB.

This will now be described in more detail with reference to FIG. 5.

As shown in FIG. 5, the PIB, initial system information that can beobtained after the SCH, can be obtained after the terminal 100 performscell searching in a particular cell. Such PIB may include only staticinformation in the cell. In this case, once the terminal 100 accuratelyreceives the PIB one time in the particular cell, it does not need toreceive the PIB again in the corresponding cell. The PIB is periodicallytransmitted via a static broadcast channel. A single PIB is broadcast ina single cell, and the PIB is periodically transmitted following aSyncCH (Synchronization Channel).

The PIB may include the following information:

-   -   Bandwidth of a current cell    -   MIB indication information (Reference): The MIB indication        information (Reference) includes a difference (i.e., time        interval) between a transmission time of the PIB and that of the        MIB (‘To’ in FIG. 5), and parameters of physical layer for        receiving the MIB. Here, the value ‘To’ may be different to be        used for each cell or according to a bandwidth of a cell. Or,        the value ‘To’ may be fixed as a particular value in every LTE        system. If the value ‘To’ is fixed as a particular value, it        does not need to be transmitted through the PIB. Namely, if the        MIB is statically transmitted and if, for example, a frequency        and a time for transmitting the MIB are fixed, the PIB may not        include the MIB indication information.

PLMN ID, BCCH cycle information: The PIB may additionally include PLMNID and BCCH cycle information. The BCCH cycle is a cycle in which systeminformation is transmitted through the BCCH (Broadcast Control Channel).For example, the BCCH cycle is a cycle of transmission of the PIB or theMIB. Or, the BCCH cycle is a cycle of transmission of the SynCH channel.

-   -   Value tag: The PIB may additionally include a Value tag. The        Value tag indicates a changed matter of the PIB, the MIB, the        SIB, etc. Thus, the terminal 100 may recognize whether or not        the PIB, the MIB, the SIB, etc., has been changed through        content of the Value tag. If the PIB does not include the Value        tag, the Value tag may be included in the MIB.

The MIB is periodically transmitted via a dynamic broadcast channel.Only a single MIB is periodically transmitted in a single cell. The MIBmay include the following information:

-   -   Value tags with respect to PIB, MIB, SIB, etc: If the PIB does        not include a value tag, the value tag may be included in the        MIB. The value tag indicates a changed matter of the PIB, the        MIB, the SIB, etc. Thus, the terminal 100 may recognize whether        or not the PIB, the MIB, the SIB, etc., has been changed through        content of the MIB.    -   SIB indication information (Reference): The SIB indication        information includes information about SIBs transmitted in a        corresponding BCCH cycle in which a corresponding MIB is        transmitted, for example, pointers for various SIBs, namely, one        or more of transmission scheduling information of SIBs and        parameters of physical layer for receiving SIBs.    -   Cell access restriction parameters (PLMN id, Tracking Area id,        cell barring, etc.)    -   RACH (Random Access Channel) access information: The MIB may        include information on accessing a RACH.

The MIB is transmitted following the PIB. The MIB is transmitted in timedifference by the value ‘To’ from the PIB. In this case, if the value‘To’ is fixed, the terminal 100 may recognize that the MIB istransmitted in a time frame after ‘To’ from the PIB transmission frame.However, even if the value ‘To’ is not fixed, because the PIB indicatesa frame of a dynamic BCH channel through the MIB is transmitted, theterminal 100 can recognize a frame through the MIB is transmitted, byreceiving the PIB.

An L1/L2 control channel, namely, a PDCCH, indicates within whichresource block the MIB is comprised, among resource blocks in the frameindicated by the value ‘To’. The terminal 100 receives the L1/L2 controlchannel in the frame, and receives a specific resource block in theframe corresponding to the MIB according to the control informationtransmitted by the L1/L2.

A bandwidth in which the MIB is transmitted may be fixed. In this case,the MIB transmission bandwidth may be set to be different depending onthe size of a cell bandwidth.

The MIB is dynamically scheduled in the frame. Accordingly, unicast dataand the MIB may be transmitted by dynamically sharing radio resources.In this case, the L1/L2 control channel provides control informationabout the transmission of the unicast and transmission of the MIB anddynamically schedules the unicast and the MIB together.

The MIB may be re-transmitted using Hybrid ARQ method without uplinkfeedback information. In this case, control information about there-transmission may be transferred via the L1/L2 control channel or thePIB to the terminal 100.

The SIB (Secondary system Information Block) may include various systeminformation which are not included in the PIB and the MIB. For example,the SIB may include setting information of a common channel or a sharedchannel, call transmission information, a cell select parameter, apositioning parameter, an MBMS parameter, etc.

The SIB is periodically transmitted via a dynamic broadcast channel, forexample, via a dynamic BCH. Mutually different SIBs may be periodicallybroadcast in each different cycle according to requirements for eachSIB. In this case, the information on cycle of the SIBs may betransmitted via the MIB as mentioned above. Namely, as described above,the MIB informs about frames of the dynamic broadcast channel throughwhich the SIBs are transmitted by using a pointer with respect to theSIBs. And where the SIBs are located in the informed frame is indicatedby the L1/L2 control channel, namely, the PDCCH. Accordingly, the SIBsmay be dynamically scheduled within the frames.

Accordingly, the terminal 100 may know the frame in which the particularSIB is transmitted by receiving the MIB. And the terminal 100 receivesthe L1/L2 control channel in the frame indicated in the MIB, andreceives a resource block in which the SIB is comprised according to thecontrol information transmitted by the L1/L2 control channel.

The SIB may be re-transmitted using Hybrid ARQ method without uplinkfeedback information. In this case, the control information with respectto the re-transmission may be transferred to the terminal 100 via theL1/L2 control channel or the PIB or the MIB.

The transmission and reception of the PIB, the MIB and the SIB will nowbe described.

An RRC 240 of the eNB 200 divides the system information into the firstto third blocks and transmits each block via the static broadcastchannel or the dynamic broadcast channel.

In detail, the RRC 240 of the eNB 200 transmits the PIB corresponding tothe first block via the static broadcast channel, and the MIBcorresponding to the second block and the SIB corresponding to the thirdblock via the dynamic broadcast channel.

Second layers 220 and 230, lower layers of the RRC layer 240 of the eNB,transfer the PIB, which has been transmitted via the static broadcastchannel, to a physical layer 210 as it is without adding a header of thesecond layer. Meanwhile, the second layers 220 and 230 of the eNB maysegment or concatenate the MIB or the SIB transmitted via the dynamicbroadcast channel, and add a header of the second layer to the MIB orthe SIB and transfer the same to the physical layer 210. The addedheader includes information about segmentation or concatenation whichhas been applied for the MIB or the SIB.

A physical layer 110 of the terminal 100 receives the PIB via the staticchannel. For example, the terminal 100 receives the PIB via the staticbroadcast channel following an SCH (Synchronization Channel). And, thephysical layer 110 of the terminal 100 transfers the received PIB to thesecond layers 120 and 130 of the terminal. The second layers 120 and 130transfer the received PIB to an RRC layer 140 as it is. The terminal 100acquires indication information about the MIB through the PIB.

The terminal 100 receives a frame including the MIB via the dynamicbroadcast channel according to the indication information. And, theterminal checks where a transmission block including the MIB is locatedin the frame via the L1/L2 control channel, namely, the PDCCH, of theframe, and receives the transmission block according to a checkedposition. The physical layer 110 of the terminal 100 transfers thetransmission block including the MIB to the second layers 120 and 130,and the second layers 120 and 130 reassemble the transmission blockbased on a header of the second layers added to the block. The secondlayers 120 and 130 of the terminal 100 transfer the reassembled MIB tothe RRC layer 140. The RRC layer 140 checks instruction matters withrespect to the SIBs included in the MIB, namely, pointers with respectto the SIBs, and instructs the physical layer 110 to receive the SIBs.

The physical layer 110 receives a frame including the SIB via thedynamic broadcast channel according to the pointer with respect to theSIB. And, the terminal 100 checks where the transmission block includingthe SIB is located in the frame through the L1/L2 control channel of theframe, and receives the transmission block according to the checkedposition.

Then, the physical layer 100 transfers the transmission block includingthe SIB to the second layers 120 and 130, and the second layer 120 and130 reassemble the transmission block based on the header of the secondlayers added to the block. The second layers 120 and 130 of the terminaltransfer the reassembled SIB to the RRC layer 140.

Although the preferred embodiments of the invention have been disclosedfor illustrative purposes, those skilled in the art will appreciate thatvarious modifications, additions and substitutions are possible, withoutdeparting from the scope and spirit of the invention as disclosed in theaccompanying claims.

As so far described, in the present invention, because systeminformation is divided into first to third blocks and transmitted, itcan be effectively transmitted.

In addition, the first block is transmitted via a static broadcastchannel while the second and third blocks are transmitted via a dynamicbroadcast channel, so the radio resources can be effectively used.

What is claimed is:
 1. A method for receiving system information via abroadcast control channel (BCCH), the method comprising: receiving, by auser equipment (UE), a block of first system information from a basestation via a broadcast channel (BCH) to which the BCCH is mapped;receiving, by the UE, a first block of second system information fromthe base station via a downlink shared channel (DL_SCH) to which theBCCH is mapped, wherein the first block of second system information isscheduled with a fixed time offset from the received block of firstsystem information; and receiving, by the UE, a plurality of secondblocks of second system information from the base station via theDL_SCH.
 2. The method of claim 1, wherein the first block of secondsystem information includes scheduling information for the plurality ofsecond blocks of second system information, and wherein the schedulinginformation includes at least one of periodicity information and mappinginformation.
 3. The method of claim 1, wherein the DL_SCH supports ahybrid automatic repeat request (HARQ) scheme.
 4. The method of claim 1,wherein the block of first system information includes at least one ofbandwidth information and parameter information about a physical layer.5. The method of claim 1, wherein the first block of second systeminformation and each of the plurality of second blocks of second systeminformation are received via the DL_SCH in accordance with frequency andtime information.
 6. The method of claim 1, wherein the plurality ofsecond blocks of second system information further includes at least oneof: paging information, a cell select related information, a positioningrelated information, and a Multimedia Broadcast Multicast Service (MBMS)related information.
 7. The method of claim 1, wherein the first blockof second system information further includes value tag information andcell access related information, and wherein the cell access relatedinformation includes at least one of Public Land Mobile Network (PLMN)identity information, tracking area information, and cell barredinformation.
 8. The method of claim 1, wherein one of the plurality ofsecond blocks of second system information further includes value taginformation.
 9. The method of claim 1, wherein the plurality of secondblocks of second system information received from the base station viathe DL_SCH is configured to carry user traffic.
 10. The method of claim1, wherein the BCH is a static channel.
 11. A method for transmittingsystem information via a broadcast control channel (BCCH), the methodcomprising: transmitting, by a base station, a block of first systeminformation to a user equipment (UE) via a broadcast channel (BCH) tothe BCCH is mapped; transmitting, by the base station, a first block ofsecond system information to the UE via a downlink shared channel(DL_SCH) to which the BCCH is mapped, wherein the first block of secondsystem information is scheduled with a fixed time offset from thereceived block of first system information; and transmitting, by thebase station, a plurality of second blocks of second system informationto the UE via the DL_SCH.
 12. The method of claim 11, wherein the firstblock of second system information includes scheduling information forthe plurality of second blocks of second system information, and whereinthe scheduling information includes at least one of periodicityinformation and mapping information.
 13. The method of claim 11, whereinthe DL_SCH supports a hybrid automatic repeat request (HARQ) scheme. 14.The method of claim 11, wherein the block of first system informationincludes at least one of bandwidth information and parameter informationabout a physical layer.
 15. The method of claim 11, wherein the firstblock of second system information and each of the plurality of secondblocks of second system information are received via the DL_SCH inaccordance with frequency and time information.
 16. The method of claim11, wherein the plurality of second blocks of second system informationfurther includes at least one of: paging information, a cell selectrelated information, a positioning related information, and a MultimediaBroadcast Multicast Service (MBMS) related information.
 17. The methodof claim 11, wherein the first block of second system informationfurther includes value tag information and cell access relatedinformation, and wherein the cell access related information includes atleast one of Public Land Mobile Network (PLMN) identity information,tracking area information, and cell barred information.
 18. The methodof claim 11, wherein one of the plurality of second blocks of secondsystem information further includes value tag information.
 19. Themethod of claim 11, wherein the plurality of second blocks of secondsystem information transmitted from the base station via the DL_SCH isconfigured to carry user traffic.
 20. The method of claim 11, whereinthe BCH is a static channel.